Preparation of alpha-dicarbonyl derivatives from beta-ketosulfoxides



United States Patent Ofice 3,409,674 PREPARATION OF a-DICARBONYL DERIVATIVES FROM B-KETOSULFOXIDES Theron L. Moore, Norfolk, Va., assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Dec. 22, 1966, Ser. No. 603,738

8 Claims. (Cl. 260592) ABSTRACT OF THE DISCLOSURE A process for preparing a-dicarbonyl derivatives from fi-ketosulfoxides by acidic rearrangement in an acid liquid provides for processes whereby either aliphatic or aromatic a-dicarbonyl derivatives are synthesized and recovered in excellent yield from fi-ketosulfoxide vides processes rivatives are easily manipulated and In most reactions the acetal derivatives are completely equivalent to, and can be directly substituted for, the corresponding u-dicarbonyl compound. In the event that and D. A. Davenport, Journal of the American Chemical 4019 (1961), although the synthesis is difiitwo-fold. First, an acidic rearrangement of the Pummerer type leads to a reaction mixture of the desired 3,409,574 Patented Nov. 5, 1968 Accordingly, it is an'object of this invention to prepare a-dicarbonyl derivatives by methods which avoid the aforesaid defects before indicated are inherent.

It is a more specific object of this invention to provide processes for the synthesis of u-dicarbonyl derivatives and their corresponding a-dicarbonyl compounds from ,B-ketosulfoxides.

In general, the objects of this invention can be realized eral reaction equation, wherein R R and R are defined by heating and reacting B-ketosulfoxide precursors of aas stated above:

dicarbonyl derivatives in an acidic liquid medium or sol- 2214 vent therefor made up of (l) a member selected from the 6 OH 000m group consisting of prlmary and secondary acetal form- A T 11+ CH30H ll 1 015911 ing alcohols and water and (2) from one to about two R1 (7155113 R1CC=SR3 R1C l3SRa equivalents, per mole of fi-ketosulfoxide entering the re- R2 R,

action, of an oxidizing reagent selected from the group consisting of I Br N0 MnOg', CrO and H 0 i I2 Rdoocn RSH- RSR H1 The a-drcharbonyl derivatives so formed can be recovered 1O 1 1 m 3 3s from the reaction mixture by conventional procedures. R2

The presence of the oxidizing reagent, as explained more fully hereinbelow, results in the increased yield of re- The removal f h me captan (B) by the oxidizing coverable a-dicarbonyl derivatives and minimizes the foraction of the iodine to form the disulfide (c), which sub P of contaminants and 'dicarbonyl deriva' 15 fur contaminant is readily separable from the a-dicartlves comammg sulfur The use of more than one to bonyl acetal (A) by distillation, shifts the equalibrium about two molecular equivalents, preferably about 1.1 molecular equivalents, of the oxidizing reagent selected is considered wasteful of the oxidizing reagent and can result in reduced yields of the desired a-dicarbonyl product.

In addition to the foregoing acidic liquid medium components, the addition of an inert solvent as a component of the acidic liquid medium is desirable when water is used as the acetal (hydrate) forming component. The prescence of the inert solvent component is desirable to insure the solution of the fi-ketosulfoxide starting material to form a homogenous reaction mixture when water is present. Also the presence of an inert solvent is desirable to insure mobility and contact between the reaction components in the case of starting materials which are solids at room temperatures. Even when primary and secondary acetal forming alcohols are present in the acidic liquid medium, the presence of an inert solvent is not detrimental to carrying out the process of the present inven- 3 tion. Suitable inert solvents for use in the acidic liquid medium of the present invention are, for example, 1,2- dimethoxyethane (monoglyrne), bis-Z-methoxyethyl ether (diglyme), acetone, dimethyl formamide, methyethyl ketone and hexamethyl phosphoramide.

i partlcuiafly the Preparation 'dlcarbonyl f amounts of acid are not harmful. In the case where the rrvatrves according to the present invention can be carrle oxidizing reagent is not acidic in nature for example out w fi'ketosulfoxlde pr.ecursors of a'dlcarbonyl H 0 or where additional acid is deemed desirable to rivatives, which fi-ketosulfoxrdes have the general formula haste; acidic rearrangement an acidic substance, for

ample dilute sulfuric, hydrochloric, perchloric and hyto favor the formation of the ot-dicarbonyl acetal. The use of iodine is also favorable in that the hydrogen iodide formed further favors the initial acidic rearrangement.

As previously stated the reacting of the B-ketosulfoxides takes place in an acidic liquid medium comprising at least one member selected from the group consisting of primary and secondary acetal forming alcohols and water. Suitable and more commonly used acetal forming alcohols are, for example, methyl alcohol, ethyl alcohol and isopropyl alcohol. Propyl, butyl, pentyl, l-hexyl, isobutyl, secondary butyl, 2-hexyl, 3-hexyl and Z-ethyl-hexyl alcohols as well as 2-hydroxy-3-rnethyl-pentane, Z-hydroxy-3-methyl-hexane, 3 -hydroxy-4-methyl-hexane are additional examples of acetal forming alcohols suitable for use in practicing the invention. As stated above the acidic liquid medium also contains at least one equivalent, per mole of fl-ketosulfoxide entering the reaction, of an oxidizing reagent selected from the group consisting of I Br N0 1 MnO CIO.; and H 0 The presence of some of the oxidizing reagents listed above, e.g., I Br or N0 in the stated amounts will in themselves render the liquid medium sufficiently acidic. A trace or catalytic amount of acidic substance is all that is required for the rearrangement to proceed, although additional 0 0 drobromic acids or acid salts such as sodium bisulfate i' g can be used to render the liquid medium acidic.

l The common sources of the oxidizing reagents, N0

2 MI1O4, and Q05, are respectively nitric acid, potassium permanganate and potassium chromate, but other sources wherein. as defined abOVe and throughout the Pffisent of the oxidizing ions, for example sodium permanganate, specification, R is selected from the group consisting of will serve a well.

saturated aliphatic, aryl and alkaryl hydrocarbon groups Suitable fl-ketosulfoxide precursors of a-dic-arbonyl containing 1 to about 18 carbon atoms and derivatives compounds for use in practicing the present invention thereof, R is selected from the group consisting of hya for example, 2-ket0undecyl methyl sulfoxide, 2'-

drogen and saturated aliphatic hydrocarbon groups conmethylsulfinyl-4-rnethoxyacetophenone, 2-methylsulfinyltaining 1 to about 4 carbon atoms and R is an aliphatic acetophenone, 2-methylsulfinyl-4-methylacetophenone, 2-

hydrocarbon group containing 1 to about 4 carbon atoms. ketononadecyl methyl sulfoxide, 2 methylsulfinyl-4- Said B-ketosulfoxide precursors of a-dicarbonyl derivafiuoroacetophenone, 2'-methylsulfinyl 2 methylacetotives are heated with provision for reflux for about 0.2 phenone, 2-ketodecy1 methyl sulfoxide, 2-ketopentadecyl hour to about 2 hours, preferably about 0.5 hour to about methyl sulfoxide, 2-ketopentyl methyl sulfoxide, 2-keto-4- 1.0 hour, at a temperature of about 25 C. to about 100 methylpentyl methyl sulfoxide, 2-methylsulfinyl-3-oxo- C. to cause their reaction in an acidic liquid medium as pentane, 2-methylsulfinyl-3-0Xo-dodecane, 2-methylsulfistated above. nyl-3-oxo-butane, 5 butanesulfinyl-6-oxo-tetracosane, 2- It has also been found preferable in the case where methylsulfinyl-3-oxo-hexane and Z-ketopentyl methyl sulfbromine is used as the oxidizing reagent to add the brooxide. mine after effecting the reaction, i.e. acidic rearrange- Such B-ketosulfoxide precursors of a-dicarbonyl comment, and continuing the heating about 0.5 hour to propounds can be prepared according to the processes dismote the beneficial equilibria shifts. closed in the copending application Ser. No. 444,068, filed A preferred process for the preparation of an u-dicar- Mar. 30, 1965, by Warren 1. Lyness and David E. OConbonyl acetal from a fi-ketosulfoxide in acidic liquid menor now Patent No. 3,355,494, wherein salts of sulfinyl dium using methanol as the acetal forming alcohol and carbanions are reacted with acylating agents, for example iodine (I as the oxidizing reagent by way of illustration carboxylic esters, acyl chlorides, and acid anhydrides, to proceeds, during a 0.5 hour to 1.0 hour period of heating prepare fl-ketosulfoxides.

with provision for reflux, according to the following gen- Subsequent to the reacting period the a-dicarbonyl derivative synthesized can be recovered from the reaction mixture by conventional procedures of extraction and distillation. For example, the reaction mixture can be cooled technique is not usually necessary, since any excess water forms a separate phase and is thus separated from. the organic phase containing a-dicarbonyl product.

due.

Other means of eifecting the separation and recovery a-dicarbonyl derivative from the reac- The following examples will illustrate in detail the manner in which the invention can be practiced. It will EXAMPLE I 20 grams (.086 mole) of the undecyl methyl sulfoxide, are dissolved in 100 equivalents per mole of ,B-ketosulfoxide starting material) of iodine and heated for 1 hour at 65 C. with provision When the process of Example I is carried out using one equivalent per mole of -ketosulfoxide starting material of Br N CrO or H 0 in place of the iodine the results are similar that the same a-dicarbonyl product, 1,l-dimethoxy-2-oxo-undecane results,

although the yields are found to be somewhat reduced from those obtained when iodine is used as the oxidizing reagent.

EXAMPLE II 10 grams (0.032 mole) of the sulfinyl-6-oxo-tetracosane, are dissolved in ml. of ethyl After reaction during the reflux period, the solution is cooled and the residual ethyl alcohol is substantially removed by stripping it from the solution under an absolute pressure equivalent to 20 mm. of mercury, which absolute pressure is generated by a water aspirator. The solution with the ethyl alcohol substantially removed is poured The a-dicarbonyl derivative crystallizes when the chloroform is removed to give a fair yield of a crystalline product identifiable as 5,S-diethoxy-6-oxo-tetracosane, which product is also useful as an intermediate in the preparation of a chelating agent in the manner of Example I.

EXAMPLE III solution of B-ketosulfoxide with iodine is then refluxed at 65 C. for 2 hours.

After reaction during the reflux period, the solution is of mercury. The a-dicarbonyl product is then vacuum distilled from the residue of the chloroform extraction liquor.

The distillation yields a 45% theoretical yield of 2,2- dimethoxy-3-oxo-hexane, based on the amount of B-ketosulfoxide starting material. The a-dicarbonyl product, 2,2- dimethoxy-3-oxo-hexane exhibits a pleasant floral perfume odor.

EXAMPLE IV 36.8 grams (0.32 mole) of the pentyl methyl The solution with the methyl alcohol substantially removed is then poured into ml. of water containing Q4 mole of sodium thiosulfate, and the composite solutive, l,1-dimethoxy-2-oxo-pentane, which exhibits a floral perfume note.

EXAMPLE V 5 grams (0.037 mole) of the B-ketosulfoxide, 2-methylsulfinyl-3-oxo-butane, are dissolved in 25 ml. of methyl alcohol containing 5.1 grams (0.02 mole or 1.1 equivalents per mole of fl-ketosulfoxide starting material) of iodine. A drop of sulfuric acid is added to acidify the solution, and the acidified solution is heated and refluxed for 1.5 hours at approximately 62 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual methyl alcohol substantially removed by evaporation under a water aspirator induced vacuum equivalent to an absolute pressure of mm. of mercury. An excess of solid sodium thiosulfate is added to the methyl alcohol stripped solution and stirred for approximately 10 hours. After the stirring period the excess sodium thiosulfate is filtered from the solution prior to distilling off a fair yield of the a-dicarbonyl product at atmospheric pressure.

The a-dicarbonyl product is the dimethoxyketal of biacetyl, which product exhibits a strong, somewhat butterlike, odor.

EXAMPLE VI 3.64 grams (0.02 mole) of the B-ketosulfoxide, 2- methylsulfinyl acetophenone are dissolved in ml. of isopropyl alcohol containing 3.8 grams (0.125 mole or 1.25 equivalents per mole of fi-ketosulfoxide starting material) of iodine, and the resulting solution is refluxed for 2 hours at 65 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual isopropyl alcohol is substantially removed by stripping it from the solution under a water aspirator vacuum. The solution with the isopropyl alcohol substantially removed is poured into 100 ml. of saturated aqueous sodium thiosulfate solution, and the composite solution is extracted with three successive ml. portions of chloroform. The chloroform extraction solution is dried over anhydrous magnesium sulfate whereupon the chloroform is stripped from the extraction solution by evaporation under water aspirator vacuum as was the isopropyl alcohol.

The a-dicarbonyl derivative product is then distilled from the extraction residue to separate it from disulfide by-product and any remaining alcohol. The distillation yields 4.0 grams of an oily liquid boiling at 74-74.5 C. at an absolute pressure equivalent to 0.25 mm. of mercury for a theoretical yield of 84% based on the amount of B-ketosulfoxide entering the reaction.

The a-dicarbonyl derivative is identified as 1,1-diisopropoxy-Z-oxo-2-phenylethane, which product is useful because it exhibits a weak floral, specifically heliotrope, perfume odor.

When methyl alcohol is used in place of the isopropyl alcohol in the process of Example VI, the a-dicarbonyl derivative is identified as l,l-dimethoxy-2-oxo-2-phenylethane and exhibits a pronounced heliotrope odor.

EXAMPLE VII 6.7 grams (0.031 mole) of the fi-ketosulfoxide, 2-ketodecyl methyl sulfoxide are dissolved in 50 ml. of methyl alcohol containing 5.1 grams (0.02 mole or 1.3 equivalents per mole of fl-ketosulfoxide starting material) of iodine and refluxed for 1 hour at -65 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual methyl alcohol is substantially removed by stripping it from the solution under a vacuum equivalent to an absolute pressure of 20 mm. of mercury induced by a water aspirator.

The solution with the methyl alcohol substantially removed is poured into 100 ml. of water containing 0.045 mole of sodium thiosulfate solution, and the composite solution is extracted with three successive 50 ml. portions of chloroform.

The chloroform extraction solution is dried over anhydrous magnesium sulfate whereupon the chloroform is stripped from the extraction solution by evaporation under water aspirator vacuum as was the methyl alcohol.

The a-dicarbonyl derivative product is distilled from the extraction residue to separate it from disulfide by-product and any remaining alcohol. The distillation yields an oily liquid boiling at 81-84 C. at an absolute pressure equivalent to 0.7 mm. of mercury. The a-dicarbonyl derivative is identified as l,l-dimethoxy-2-oxo-nonane, which product is useful in that it exhibits the odor of raw coconut.

EXAMPLE VIII 46.4 grams (0.20 mole) of the fi-ketosulfoxide, 2 ketoundecyl methyl sulfoxide, are dissolved in 300 ml. of water together with 200 ml. of 1,2-dimethoxy-ethane (monoglyme) containing 30.0 grams (0.12 mole or 1.2 equivalents per mole of fl-ketosulfoxide starting material) of iodine. The resulting solution is heated and refluxed for one hour at approximately C. After reaction during the refluxing period, the solution is allowed to cool and the residual monoglyme is substantially removed from the solution by evaporating it under a water aspirator vacuum.

An excess of sodium thiosulfate is added to the aqueous solution with the monoglyrne substantially removed, and the composite solution is extracted with three successive 50 ml. portions of chloroform. The chloroform extraction solution is then dried over anhydrous magnesium sulfate before stripping off the chloroform under water aspirator vacuum.

The a-dicarbonyl derivative crystallizes as a white crystalline product in a yield of based on the amount of B-ketosulfoxide starting material. The product u-dicarbonyl derivative is identifiable as the hydrate of a-ketoundecanal (l,1-dihydroxy-2-oxo-undecane) and exhibits a floral scent.

EXAMPLE IX 10 grams (0.062 mole) of the fi-ketosulfoxide, 2-keto- 4-methylpentyl methyl sulfoxide, are dissolved in ml. of methyl alcohol containing 9 grams (0.035 mole or 1.1 equivalents per mole of B-ketosulfoxide starting material) of iodine and the solution is refluxed for 1.5 hours at 65 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual methyl alcohol is substantially removed by stripping it from the solution under a water aspirator induced vacuum generating an absolute pressure equivalent to 20 mm. of mercury.

The solution with the methyl alcohol substantially removed is poured into 100 ml. of saturated aqueous sodium thio-sulfate solution, and the composite solution is extracted with three successive 50 ml. portions of chloroform. The chloroform extraction solution is then dried over anhydrous magnesium sulfate whereupon the chloroform is stripped from the extraction solution under water aspirator vacuum as was the methyl alcohol.

The a-dicarbonyl derivative is distilled at atmospheric pressure from the extraction residue to separate it from disulfide by-product and any remaining alcohol.

The distillation results in a moderate yield of an oily liquid, which liquid exhibits a floral scent and is identifiable as 1,1-dimethoxy-2-oxo-4-methy1 pentane by spectral means.

EXAMPLE X 1.7 grams (0.008 mole) of the B-ketosulfoxide, 2'- methyl-sulfinyl-4-methoxyacetophenone, are dissolved in 50 ml. of methyl alcohol containing 1.2 grams (0.0048 mole or 1.2 equivalents per mole of ,B-ketosulfoxide starting material) of iodine. The resulting solution is refluxed for 2 hours at approximately 60 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual methyl alcohol is substantially removed by stripping it from the solution by evaporation under a water aspirator induced vacuum generating an absolute pressure equivalent to 20 mm. of mercury.

The solution with the methyl alcohol substantially removed is poured into 125 ml. of saturated aqueous thiosulfate solution, and the composite solution is extracted with three successive 50 ml. portions of chloroform. The chloroform extraction solution is then dried over anhydrous magnesium sulfate whereupon the chloroform is stripped from the extraction solution under water aspirator vacuum as was the methyl alcohol.

The u-dicarbonyl derivative product is vacuum distilled from the extraction residue to separate it from disulfide by-product and any remaining alcohol.

The distillation results in a 91% of theoretical yield, based on the amount of fi-ketosulfoxide employed in the reaction, of an a-dicarbonyl derivative in the form of white crystals having a melting point of 63.5 C.-64.5 C. The a-dicarbonyl derivative is identifiable as the dimethylacetal of p-methoxyphenylglyoxal (1,1-dimethoXy-2-0x0- Z-p-methoxyphenylethane) and exhibited a pleasant floral spice odor reminiscent of heliotrope.

EXAMPLE XI 8.8 grams (0.06 mole) of the ,B-ketosulfoxide, 2 methylsulfinyl-3-oxo-pentane, are dissolved in 50 ml. of methyl alcohol containing 8 grams (0.0048 mole or 1.1 equivalents per mole of ,B-ketosulfoxide starting material) of iodine and refluxed for 1.5 hours at 60-65 C.

After reaction during the refluxing period, the solution is allowed to cool and the residual methyl alcohol is substantially removed by evaporating it from the solution under a water aspirator induced vacuum generating an absolute pressure equivalent to 20 mm. of mercury. The solution with the methyl alcohol substantially removed is poured into 100 ml. of saturated aqueous sodium thiosulfate solution to accomplish neutralization, and the methyl alcohol.

The a-dicarbonyl derivative is distilled from the extraction residue to separate it from disulfide by-product as well as any remaining alcohol. The distillation yields 9.3 grams of an oily liquid identifiable by spectral means as the dimethyl-ketal of 2,3-dioxopentane which exhibits a butter-like odor.

EXAMPLE XII grams (0.022 mole) of the S-ketosulfoxide starting material of Example I, Z-ketoundecyl methyl sulfoxide, are dissolved in 50 ml. of methyl alcohol containing 1 ml. of sulfuric acid. The solution is then heated and refluxed for 30 minutes whereupon the solution is cooled to room temperature. After cooling to room temperature, 1.23 grams of an aqueous solution, containing 30% by weight of hydrogen peroxide and providing 1 equivalent per mole of fl-ketosulfoxide starting material, are added to the solution in a dropwise manner. The solution with the hydrogen peroxide added was stirred at room temperature for an hour before stripping the methyl alcohol from the solution by evaporation under water aspirator vacuum. The a-dicarbonyl product is then extracted from the solution with two successive 25 ml. portions of choloroform.

The combined portions of chloroform extraction solu- 10 EXAMPLE XIII an 84% ketosulfoxide starting material.

EXAMPLE XIV 10 grams (0.043 mole) of Z-ketoundecyl methyl sulfoxrde, the fi-ketosulfoxide starting material of Example I,

EXAMPLE XV 10.3 grams (0.03 mole) of the nonadecyl methyl sulfoxide, are dissolved in ml. of

1,1-dimethoxy-2-oxo-nonadecane. The amount of product 18 equivalent to 44% of the theoretical yield calculated from the starting amount of ,B-ketosulfoxide.

EXAMPLE xvr mole) of the B-ketosulfoxide, 2-methyl sulfinyl-4-fluoroacetophenone, are dissolved in 50 ml. of methyl alcohol together with 2.0 grams (0.008 mole or 1.6 equivalents per mole of fi-ketosulfoxide starting material) of iodine. The solution is then heated with provision for reflux for 1.5 hours. After reaction during the refluxing period, the solution is allowed to cool, and the residual methyl alcohol is substantially removed by evaporating it from the solution under water aspirator vacuum.

The solution with the methyl alcohol substantially removed is poured into 100 ml. of saturated sodium thiosulfate solution, and the composite solution is extracted with three 50 ml. portions of chloroform. The composite portions of chloroform extraction solution are then dried over anhydrous magnesium sulfate, after which the chloroform is stripped from the extraction solution under water aspirator vacuum as was the methyl alcohol.

The a-dicarbonyl derivative is vacuum distilled from the residue to separate it from the disulfide by-product as well as any remaining alcohol. The distillation product is identified as 1,1-dimethoxy-2 oxo 2 p fluorophenylethane, which product exhibits a floral scent.

While specific examples of methods embodying the present invention have been described above, it will be apparent that many changes and modifications may be made in the methods of procedure without departing from the spirit of the invention. It will be understood, therefore, that the examples cited and the procedures set forth are intended to be illustrative only and are not intended to limit the invention.

Having thus described the invention, what is claimed is:

1. A process for the production of an a-dicarbonyl derivative from a B-ketosulfoxide having the structure 2 grams (0.01

H t R16 CH S R3 R2 wherein R is selected from the group consisting of alkyl, aryl and alkaryl containing 1 to about 18 carbon atoms,

fluorophenyl and methoxyphenyl, R is selected from the group consisting of hydrogen and saturated aliphatic hydrocarbon groups containing 1 to about 4 carbon atoms and R is a saturated aliphatic hydrocarbon group containing 1 to about 4 carbon atoms, which process comprises the steps of:

(1) dissolving said fl-ketosulfoxide in an acidic liquid medium therefor, which acidic liquid medium contains a member selected from the group consisting of primary and secondary acetal forming alcohols and water together with 1 to about 2 equivalents per mole of fl-ketosulfoxide of an oxidizing agent selected from the group consisting of 1 Br [N0 1 M1104", C1'04:]HN03, KMnO K2 CI'O4 and H202, and

(2) reacting the solution so formed at a temperature of about 25 C. to about C. with provision for reflux for a period of about 0.2 hour to about 2 hours.

2. The process of claim 1 wherein the oxidizing agent is 1 and the acidic liquid medium contains methyl alcohol.

3. The process of claim 1 wherein the heating and reacting is carried out for a period of about 0.5 hour to about 1 hour.

4. The process of claim 1 wherein about 1.1 equivalents of the oxidizing agent selected from the group consisting Of I2, Bl'g, [NO3' MDO4 CI'O4=] HNO3, KMHO4, K CrO and H 0 are present per mole of p-ketosulfoxide.

5. The process of claim 1 wherein Br is the oxidizing agent and is added to the acidic liquid medium in step 2, subsequent to reaction and prior to the end of the reacting period.

6. The process of claim 1 wherein the acidic liquid medium for the B-ketosulfoxide contains water and inert solvent.

7. The process of claim 1 wherein an inert solvent is present in the acidic liquid medium of step 1.

8. The process of claim 1 wherein the acidic liquid medium of step 1 is rendered acidic by the addition of an acidic substance selected from the group consisting o dilute sulfuric, hydrochloric, perchloric and hydrobromic acids and sodium bisulfate salts.

References Cited Kenney et al. J. Am. Chem. Soc. 83 4019-4022 (1961).

DANIEL D. HORWITZ, Primary Examiner. 

